A widespread thought going into the Stanley Cup final was the Sharks might have a slight edge because of their depth. What that lost was the Penguins are playing as more than the sum of their parts.

It showed as the Pens took a 1-0 lead in the best-of-seven series with a 3-2 victory in Game 1 in Pittsburgh on Monday night. Nick Bonino, who is hardly a household name, scored the game-winner with 2:33 remaining. The Boston University product from Hartford, Conn., is not an upper-echelon player, but once he started centering Carl Hagelin and Phil Kessel, the unit (known as the HBK line) has been as consistently good as any in the postseason.

It’s the type of third line that great teams are made of. But it’s made possible by Conor Sheary, 23 years old and just two years out of UMass-Amherst, skating on the top line with Sidney Crosby. That’s enabled Chris Kunitz to leave Crosby’s side and help Evgeni Malkin on the second line — which has a 24-year-old right winger by the name of Bryan Rust, two years out of Notre Dame.

Sheary and Rust scored the first two goals of the game, 62 seconds apart in the first period, before Bonino won it. Crosby was the best player on the ice all night, on the puck and playing with what seems to be a rejuvenated sense of determination. But that’s what expected of him. It’s the role players for the Penguins who are playing above their heads, and have been for a long time.

And that makes the Sharks look like a better team — on paper. Crosby has Sheary on his wing, while Joe Thornton’s top line in San Jose has Tomas Hertl and Joe Pavelski. Their second line of Patrick Marleau-Logan Couture-Jonas Donskoi is formidable, as well, while big-game winger Joel Ward is on the third line and Tommy Wingels is on the wing for a talented fourth line.

Where the Sharks look a lot better (on paper) is on the back end. Marc-Edouard Vlasic and Justin Braun make for a terrific shutdown pair, and Paul Martin and Brent Burns are the offensive counter-punch from the blue line. Brendan Dillion and Roman Polak are as good a third pair as there has been this postseason.

Yet as good as season as Burns had, he is not on the same level as Letang. On the game-winner, Letang showed the instinct to carry the puck into the zone, then the jaw-dropping vision to maneuver around Burns to find Bonino in front. Next to Letang, Brian Dumoulin hasn’t exactly been a powerhouse, and neither was the young Olli Maata when he got that chance. But Letang makes all those around him better, and he is good enough to carry the load.

Same can be said for Crosby and Malkin up front, but they still need the role players to be capable of finishing great plays. Since Mike Sullivan took over behind the bench in December, that is exactly what has happened with the Penguins. It’s why they have been the best team in the league since then and why they won Game 1.

The Sharks still may prove to better, just as they look on paper. But if the Penguins keep being more than the sum of their parts, then they might be unstoppable.